1. Field of the Invention
The invention is an improved process for preparing amino polyols. In particular, the invention is an improved process for making polyols which are used in preparing polyurethane or polyisocyanurate foams. Specifically, the invention is an improvement to U.S. Pat. No. 3,297,597 (Edwards et al.) patented Jan. 10, 1967.
2. Description of the Prior Art
U.S. Pat. No. 3,297,597 (Edwards et al.) describes the reaction of an alkylene oxide with the Mannich condensation product of a phenolic compound with formaldehyde and an alkanolamine. The Edwards et al. patent was a pioneer in the field. Accordingly, numerous improvements to the Edwards et al. patent have been made.
U.S. Pat. No. 4,499,264 is an improvement to the Edwards et al. patent which concerns charging ammonia or amines to the reaction vessel at the end of the alkylene oxide digestion step. The degree of alkylene oxide digestion is equilibrium limited. The ammonia or amine scavenges the residual alkylene oxide and the resulting alkanolamine becomes one of the components in the polyol mixture.
U.S Pat. No. 4,137,265 (Edwards et al.) is directed to Mannich condensates prepared by reacting a phenolic compound with formaldehyde and diethanolamine which are then propoxylated and used in the manufacture of rigid polyurethane foam.
U.S. Pat. No. 4,500,655 (Brennan) describes a polyol prepared by reacting a propoxylation product with melamine and a lower alkylene carbonate. The propoxylation product; which may contain ethylene oxide is prepared by propoxylating a condensate of phenol or a C.sub.1 to C.sub.12 alkylphenol with formaldehyde and diethanolamine in the mole ratios of 1:1:1 to 1:3:3.
U.S. Pat. No. 4,489,178 (Brennan et al.) describes Mannich condensates of phenol, formaldehyde and diethanolamine in which a minor amount of melamine is dissolved subsequent to alkoxylation with propylene oxide or a mixture of propylene oxide and ethylene oxide.
U.S. Pat. No. 4,487,852 (Brennan et al.) describes Mannich condensates of phenol, formaldehyde and an amine mixture consisting of diethanolamine and melamine which is alkoxylated with propylene oxide or a mixture of propylene oxide and ethylene oxide.